Mixing device



/ 7, 1951 w. w. BlSSELL ET AL 2,563,002

MIXING DEVICE Filed Oct. e, 1948 INVENTORS: r; Delmar G. Debo Q & William W; Bissel/ 5 Wig/5661M A T'TO/M/E Y Patented Aug. 7, 1951 ff'UNlT-ED STATES PATENT OFFICE William W. Bissell, New Castle, Pa., and Delmar G. Debo, Chicago, 111., assignors to Standard :Oil Company, Chicago, 111., a corporation of Indiana Application October 6, 1948, Serial No. 53,046

4 Claims.

. 1 g This application relates to apparatus for injection of a liquid, especially a corrosive liquid, into admixture with a liquid flowing in a pipe.

- A treatment of liquids with other fluids or the proportioning of liquids, and particularly their proper admixture when the liquids are immiscible has required the development of diverse mixing devices, such, for example, as turbine or pump mixers. When the treating fluid, which is ordinarily added in minor proportion, is corrosive to the conduit. transporting or pump handling the liquid of major proportion, the aforesaid mixers have necessarily been made of resistant alloys which are in many instances prohibitively expensive. The simple injection, on the other hand, of such a corrosive liquid even into the center of a stream of liquid flowing in a pipe results in rapid corrosionof the pipe near the point of introduction of the corrosive liquid.

It is a primary object of the present invention to provide simple, relatively inexpensive means for introducing a corrosive liquid into and effectively mixing it with another liquid.

It is another object of the invention to provide simple means whereby a corrosive liquid can be admixed with a liquid flowing in a pipe and may be rapidly intermixed therewith so that the pipe at the downstream point of the admixture will not be subjected to the corrosive action of the introduced liquid.

The invention has, for other objects, those other advantages or results as will appear in the following description of the apparatus of invention.

The foregoing objects are accomplished in simple manner by providing a pipe spool of standard dimensions in which is inserted a Venturi tube, preferably of resistant alloy material, about the throat of which tube there is encircled a pipe ring to which, in turn, there is attached piping which feeds from an extraneous source the corrosive liquid additive; As will appear more clearly in the detailed description of the drawings hereinafter supplied,thesaid Venturi-type tube is fitted into the pipe spool and includes a protective sleeve which is an extension of the down stream side of the Venturi tube, the said sleeve being annularly contiguous with the aforesaid pipe spool. The introduction of the corrosive liquid additive at the Venturi throat advantageously exploits the turbulence provided by the Venturi tube so that a rapid mixing of treated liquid and liquid additive is obtained. While the tube is preferably constructed of a resistant alloy and will, in such instances, provide uninterrupted service, it can be made of ordinary materials and will nevertheless have an extended life because of the enhanced mixing provided by the described device of introducing the corrosive liquid additiveat the said Venturi throat. The Venturi can insuch instances be readily removed from the pipe spool when corrosion has set in. It is preferable, however, to construct the Venturi tube of a resistant alloy. A further improvement provided by the present apparatus permits the employment of thin gauge sheet in the manufacture of the said Venturi tubes so that the initial expense when resistant alloys are employed is itself reduced. This improvement consists of providing holes in the conical interfaces of both the inlet and outlet cones of the Venturi tube, these holes being arranged circularly near the base of each cone. In this manner, a small flow of liquid is permitted in the space between the Venturi tube of the pipe and thereby several advantages are obtained. The pressure differential across the Venturi walls will be substantially eliminated and, therefore, extremely thin walls can be employed. The outside pipe, usually of carbon steel, is thereby maintained at the same temperature as the Venturi tube, thus minimizing thermal expansion difierences between the pipes and the Venturi tubes, and the flow of oil in the annular space around the Venturi eliminates a dead space and prevents either accumulation of any corrosive materials in this space or the tendency of coke formation.

In the accompanying drawing, which is provided solely for purposes of illustration, Fig. 1 is a cross sectional, longitudinal view of a preferred apparatus embodying the features of the invention, and Fig. 2 is a cross-section taken along the line II--II of Fig. 1 and showing a side view of the injection device employed for introducing the corrosive liquid additive.

Referring now to Fig. 1, there is mounted in a pipe spool 2 of ordinary material, a Venturi tube 4 constructed of a resistant alloy. The Venturi-tube conventionally consists of a short conical inlet section 6, a throat 8, and an elongated conical outlet section III. An extension I2 of the Venturi tube down stream thereof is of a length approximately equal to that of the Venturi tube and fits as an inner sleeve annularly contiguous against the said pipe spool 2. The Venturi tube 4 is fitted at the circular base [4 of the inlet section 6 of the Venturi tube against the up-stream flange it of the pipe 2. Preferably, the circular base [4 is seated in a recess in the flange l6, relative movement caused by differences in thermal expanson of the tube and of the pipe being permitted by the fact that the sleeve I2 is not fixed in the pipe 2 but can slide therein.

Annularly arranged around the inlet section 6 a short and uniform distance from the base I4 are equidistantly spaced holes ll. Similarly arranged are equidistantly spacedholes l8 placed a short uniform distance from the down-stream end of outlet section Iii. These holes permit a slight flow of liquid between the Venturi tube 4 and pipe spool 2 thus reducing the pressure on the Venturi tube and permitting its manufacture of thin sheet metal, and also protecting the inner wall of the pipe from corrosion by accidental con- 7 tact with liquid additive.

An injection feeder pipe i9 is attached at right angles to the longitudinal dimension of the pipe 2 and extends through the wall of the pipe to the throat S of the Venturi tube. The pipe i9 is provided with a flange 20, packing gland 22 and an outer sleeve 24 so that the pipe 19 can readily be removed from communication with the said Venturi tube. Encircling the Venturi throat 8 at about the longitudinal center thereof is an annularly fitted tube or ring 25 consisting of a longitudinally split pipe. The tube formedv by the semi-pipe section is welded around the said throat so that the throat itself forms half of the conduit provided by the ring 25. That part of the throatv 8. which provides the inner wall of the ring-like conduitZlsw is perforated with holes 28 spaced equally apart. Usually some twelve to twenty-four holes are employed and these are of varying dimension so that a uniform flow of additive. is injected from every point around the Venturi throat. The said ring 26 is connected with the secondary pipe ie with a hreaded coupling 39.

The section IIII illustrates a sectional view of the annular ring 25 and shows more clearly the positionof the holes 28 and the attached coupling 36 welded thereto.

A pipe connection can be supplied between the up-stream side of the pipe spool and a tank not shown providing the supply of corrosive additive liquid so that the characteristic decrease in pressure at the throat of the Venturi can be utilized for increasing the force of injection of additive liquid.

. In one example in which the above described device was employed, an aqueous caustic solution was introduced through the injection pipe i9 and was injected through the-holes 28 into sour oil flowing from left to right (as shown on the drawing) through the pipe 2. In this instance, the Venturi tube, the annular ring and the feeder pipe 19 was made of an 188 alloy containing approximately 73% iron, 18% chromium, 8-9% nickel and 0.5% manganese. The tube proper was of A; inch thickness and the extended sleeve of only inch thickness. Twelve M inch diameter holes were equidistantly spaced around the base of the inlet section and an equal number were arranged in the outlet section near the base thereof. A slow flow of the oil through the annular space between the Venturi tube and the pipe provided the hereinabove, described advantages. A mixing device as above described has been used for a period three times as long as the longest period during which previous devices were usable and yet no indication of corrosion has arisen.

Having now described our invention, what we claim is:

1. Apparatus for admixing a corrosive fluid with a liquid flowing in a pipe section, which apparatus comprises: a Venturi tube assembly longitudinally fitted within the pipe section and having an upstream cone, a downstream cone oppositely disposed along the same axis, the bases of the said cones being contiguous with the inner walls of the pipe section, and a throat disposed between the cones; a space between the said cones and throat and the said inner walls; at

least one opening in each cone adjacent the bases thereof whereby apart of the liquid flowing through the pipe section by-passes the throat of the Venturi tube assembly and flows through the space between the outer walls of the said throat and the inner Walls of the pipe section; a feeder consisting of a conduit communicating with the throat through at least one perforation in the wall of said throat; and an inlet conduit extending through a wall of the pipe section for introducing corrosive, fluid from a point outside the said pipe section to the feeder.

2. The apparatus of claim 1 wherein the one end of the Venturi tube assembly is fixed to the pipe section and the other end is free to move in response to thermal changes, the said apparatus being further characterized by a packing gland between the said inlet conduit and the said wall of the pipe section, the said inlet conduit bein removably connected to the feeder and being removable so that the Venturi tube assembly can be readily removed from the pipe section.

3., The apparatus of. claim 1 in which the Venturi tube assembly includes a cylindrical sleeve that extends from the downstream, cone and is slidable and annularly disposed within the said pipe section, substantially contiguous therewith.

4. Apparatus for admixing a corrosive fluid with a liquid flowing in a pipe section, which apparatus comprises: a Venturi' tube assembly longitudinally fitted Within the pipe section and having an upstream cone, a downstream cone oppositely disposed along the same axis, the bases of the said cones being contiguous with the inner walls of the pipe section, and a throat of smaller diameter than the said section, disposed between and connecting the cones whereby a space is provided between the said cones andthroat and the said inner walls; at least one. opening in each cone adjacent the bases thereof whereby a part of the liquid flowing through the pipe section bypasses the throat of the Venturi tube assembly and flows through the space. between the outer walls of the said throat and the inner walls of the pipe section; a feeder in the form of aringlike tube surrounding the throat and enclosing perforations in the throat. wall through which corrosive fluid passes from the feeder into the throat; and an inlet conduit extending through the wall of;-a pipe sectionfor introducing corrosive fluid from a point outsidethe said pipe section to the feeder.

WILLIAM W. BISSELL.

DELMER.v G. DEBO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,831,265 Schonberg Nov. 10, 1931 1,890,439 Pier Dec. 6, 1932 1,920,886 Pier et a1; Aug; 1, 1933' 2 ,075,867 Sampsel Apr. 6, 1937 2,093,011 Grosz Sept. 14, 1937 2,155,315 Kremers Apr. 18, 1939 2,307,509 Joachim'et al. Jan. 5, 1943 2,321,879 Valdez June 15, 1943 2,357,266 Malcom Aug; 29, 1944 2,361,150 Petroe Oct. 24, 1944 FOREIGN PATENTS;

Number Country" Date 585,553 Great'Britain' Feb. 11, 1947- 

